Assume that accept4 is always available and works

Simplify the Linux accept4 implementation based on the assumption
that it is available in some way.  __ASSUME_ACCEPT4_SOCKETCALL was
previously unused, so remove it.

For ia64, the accept4 system call (and socket call) were backported
in kernel version 3.2.18.  Reflect this in the installation
instructions.

3 files changed, 34 insertions, 0 deletions

diff --git a/support/Makefile b/support/Makefile
index 1f33fa0c74..38dbd832e9 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -50,6 +50,7 @@ libsupport-routines = \
   temp_file \
   write_message \
   xaccept \
+  xaccept4 \
   xasprintf \
   xbind \
   xcalloc \
diff --git a/support/xaccept4.c b/support/xaccept4.c
new file mode 100644
index 0000000000..67dd95e9fb
--- /dev/null
+++ b/support/xaccept4.c
@@ -0,0 +1,32 @@
+/* accept4 with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+int
+xaccept4 (int fd, struct sockaddr *sa, socklen_t *salen, int flags)
+{
+  int clientfd = accept4 (fd, sa, salen, flags);
+  if (clientfd < 0)
+    FAIL_EXIT1 ("accept4 (%d, 0x%x): %m", fd, flags);
+  return clientfd;
+}
diff --git a/support/xsocket.h b/support/xsocket.h
index 0dbf13ace9..d6724948d8 100644
--- a/support/xsocket.h
+++ b/support/xsocket.h
@@ -30,6 +30,7 @@ void xconnect (int, const struct sockaddr *, socklen_t);
 void xbind (int, const struct sockaddr *, socklen_t);
 void xlisten (int, int);
 int xaccept (int, struct sockaddr *, socklen_t *);
+int xaccept4 (int, struct sockaddr *, socklen_t *, int);
 void xsendto (int, const void *, size_t, int,
               const struct sockaddr *, socklen_t);
 size_t xrecvfrom (int, void *, size_t, int, struct sockaddr *, socklen_t *);